Many industrial processes require periodic or continuous monitoring and measurement of the concentration of particular chemicals dissolved in a solution. As an example, prior to discharge, treated plant wastes or sewage must be tested for the presence of particular components. Such measurements can be either "continuous" or "sampling". From the standpoint of process control, continuous measurements are preferable to sampling or batch measurements.
Prior art devices for effecting such measurements include specific ion probes, optical density devices and pH meters. A variety of each of these types of probes is well known in the art.
In general, such prior art devices do not function effectively in the continuous monitoring of plant wastes and sewage. These solutions may include a wide variety of and a relatively high concentration of chemicals (other than those being monitored). For this reason, these solutions typically require a sampling system, such as sequential titration, that isolates the chemical to be quantified from other interfering chemicals before an attempt is made to determine its concentration. Even with such conventional sampling techniques, however, the make up of the waste solution may be such that accurate results are not provided.
One specific example of a chemical that is difficult to monitor in waste water treatment, is chlorine or chlorine dioxide. While clean water can be continuously monitored for chlorine or chlorine dioxide concentration, this same measurement is normally extraordinarily difficult in plant waste or sewage solutions undergoing treatment.
There is then, a need in the art for a system that effectively and continuously monitors the concentration of particular chemicals contained in various solutions such as plant waste and sewage discharges. The method and apparatus of the present invention recognizes that such solutions can be continuously monitored by analyzing the presence of a target chemical contained in the solution as a dissolved gas. One method of effecting this analysis is by directing a stream of bubbles through the waste solution to release gases from the solution which include a quantity of the target chemical. These gases are then collected and the concentration of the target chemical is determined.
Accordingly it is an object of the present invention to provide a method and apparatus for continuously monitoring the presence and concentration of particular chemicals present in solutions such as sewage or waste water solutions. It is a further object of the present invention to provide a method and apparatus for directing a stream of bubbles through a solution and for collecting and analyzing gases stripped by the bubbles to ascertain the concentration of particular chemicals in the solution. Yet another object of the present invention to provide a method and apparatus for continuously monitoring plant or sewage waste solutions that are effective, inexpensive, and simple in operation.